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a4aebe9365
Only the posix timer system calls use this (when the posix timer support is disabled, which does not actually happen in any normal case), because they had debug code to print out a warning about missing system calls. Get rid of that special case, and just use the standard COND_SYSCALL interface that creates weak system call stubs that return -ENOSYS for when the system call does not exist. This fixes a kCFI issue with the SYS_NI() hackery: CFI failure at int80_emulation+0x67/0xb0 (target: sys_ni_posix_timers+0x0/0x70; expected type: 0xb02b34d9) WARNING: CPU: 0 PID: 48 at int80_emulation+0x67/0xb0 Reported-by: kernel test robot <oliver.sang@intel.com> Reviewed-by: Sami Tolvanen <samitolvanen@google.com> Tested-by: Sami Tolvanen <samitolvanen@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Borislav Petkov <bp@alien8.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
248 lines
8.4 KiB
C
248 lines
8.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* syscall_wrapper.h - x86 specific wrappers to syscall definitions
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*/
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#ifndef _ASM_X86_SYSCALL_WRAPPER_H
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#define _ASM_X86_SYSCALL_WRAPPER_H
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#include <asm/ptrace.h>
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extern long __x64_sys_ni_syscall(const struct pt_regs *regs);
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extern long __ia32_sys_ni_syscall(const struct pt_regs *regs);
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/*
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* Instead of the generic __SYSCALL_DEFINEx() definition, the x86 version takes
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* struct pt_regs *regs as the only argument of the syscall stub(s) named as:
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* __x64_sys_*() - 64-bit native syscall
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* __ia32_sys_*() - 32-bit native syscall or common compat syscall
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* __ia32_compat_sys_*() - 32-bit compat syscall
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* __x64_compat_sys_*() - 64-bit X32 compat syscall
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*
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* The registers are decoded according to the ABI:
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* 64-bit: RDI, RSI, RDX, R10, R8, R9
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* 32-bit: EBX, ECX, EDX, ESI, EDI, EBP
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*
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* The stub then passes the decoded arguments to the __se_sys_*() wrapper to
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* perform sign-extension (omitted for zero-argument syscalls). Finally the
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* arguments are passed to the __do_sys_*() function which is the actual
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* syscall. These wrappers are marked as inline so the compiler can optimize
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* the functions where appropriate.
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*
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* Example assembly (slightly re-ordered for better readability):
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*
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* <__x64_sys_recv>: <-- syscall with 4 parameters
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* callq <__fentry__>
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*
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* mov 0x70(%rdi),%rdi <-- decode regs->di
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* mov 0x68(%rdi),%rsi <-- decode regs->si
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* mov 0x60(%rdi),%rdx <-- decode regs->dx
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* mov 0x38(%rdi),%rcx <-- decode regs->r10
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*
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* xor %r9d,%r9d <-- clear %r9
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* xor %r8d,%r8d <-- clear %r8
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*
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* callq __sys_recvfrom <-- do the actual work in __sys_recvfrom()
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* which takes 6 arguments
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*
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* cltq <-- extend return value to 64-bit
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* retq <-- return
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*
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* This approach avoids leaking random user-provided register content down
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* the call chain.
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*/
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/* Mapping of registers to parameters for syscalls on x86-64 and x32 */
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#define SC_X86_64_REGS_TO_ARGS(x, ...) \
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__MAP(x,__SC_ARGS \
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,,regs->di,,regs->si,,regs->dx \
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,,regs->r10,,regs->r8,,regs->r9) \
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/* Mapping of registers to parameters for syscalls on i386 */
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#define SC_IA32_REGS_TO_ARGS(x, ...) \
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__MAP(x,__SC_ARGS \
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,,(unsigned int)regs->bx,,(unsigned int)regs->cx \
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,,(unsigned int)regs->dx,,(unsigned int)regs->si \
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,,(unsigned int)regs->di,,(unsigned int)regs->bp)
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#define __SYS_STUB0(abi, name) \
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long __##abi##_##name(const struct pt_regs *regs); \
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ALLOW_ERROR_INJECTION(__##abi##_##name, ERRNO); \
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long __##abi##_##name(const struct pt_regs *regs) \
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__alias(__do_##name);
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#define __SYS_STUBx(abi, name, ...) \
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long __##abi##_##name(const struct pt_regs *regs); \
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ALLOW_ERROR_INJECTION(__##abi##_##name, ERRNO); \
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long __##abi##_##name(const struct pt_regs *regs) \
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{ \
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return __se_##name(__VA_ARGS__); \
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}
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#define __COND_SYSCALL(abi, name) \
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__weak long __##abi##_##name(const struct pt_regs *__unused); \
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__weak long __##abi##_##name(const struct pt_regs *__unused) \
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{ \
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return sys_ni_syscall(); \
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}
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#ifdef CONFIG_X86_64
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#define __X64_SYS_STUB0(name) \
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__SYS_STUB0(x64, sys_##name)
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#define __X64_SYS_STUBx(x, name, ...) \
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__SYS_STUBx(x64, sys##name, \
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SC_X86_64_REGS_TO_ARGS(x, __VA_ARGS__))
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#define __X64_COND_SYSCALL(name) \
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__COND_SYSCALL(x64, sys_##name)
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#else /* CONFIG_X86_64 */
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#define __X64_SYS_STUB0(name)
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#define __X64_SYS_STUBx(x, name, ...)
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#define __X64_COND_SYSCALL(name)
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#endif /* CONFIG_X86_64 */
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#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
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#define __IA32_SYS_STUB0(name) \
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__SYS_STUB0(ia32, sys_##name)
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#define __IA32_SYS_STUBx(x, name, ...) \
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__SYS_STUBx(ia32, sys##name, \
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SC_IA32_REGS_TO_ARGS(x, __VA_ARGS__))
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#define __IA32_COND_SYSCALL(name) \
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__COND_SYSCALL(ia32, sys_##name)
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#else /* CONFIG_X86_32 || CONFIG_IA32_EMULATION */
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#define __IA32_SYS_STUB0(name)
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#define __IA32_SYS_STUBx(x, name, ...)
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#define __IA32_COND_SYSCALL(name)
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#endif /* CONFIG_X86_32 || CONFIG_IA32_EMULATION */
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#ifdef CONFIG_IA32_EMULATION
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/*
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* For IA32 emulation, we need to handle "compat" syscalls *and* create
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* additional wrappers (aptly named __ia32_sys_xyzzy) which decode the
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* ia32 regs in the proper order for shared or "common" syscalls. As some
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* syscalls may not be implemented, we need to expand COND_SYSCALL in
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* kernel/sys_ni.c to cover this case as well.
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*/
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#define __IA32_COMPAT_SYS_STUB0(name) \
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__SYS_STUB0(ia32, compat_sys_##name)
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#define __IA32_COMPAT_SYS_STUBx(x, name, ...) \
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__SYS_STUBx(ia32, compat_sys##name, \
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SC_IA32_REGS_TO_ARGS(x, __VA_ARGS__))
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#define __IA32_COMPAT_COND_SYSCALL(name) \
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__COND_SYSCALL(ia32, compat_sys_##name)
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#else /* CONFIG_IA32_EMULATION */
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#define __IA32_COMPAT_SYS_STUB0(name)
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#define __IA32_COMPAT_SYS_STUBx(x, name, ...)
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#define __IA32_COMPAT_COND_SYSCALL(name)
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#endif /* CONFIG_IA32_EMULATION */
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#ifdef CONFIG_X86_X32_ABI
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/*
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* For the x32 ABI, we need to create a stub for compat_sys_*() which is aware
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* of the x86-64-style parameter ordering of x32 syscalls. The syscalls common
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* with x86_64 obviously do not need such care.
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*/
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#define __X32_COMPAT_SYS_STUB0(name) \
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__SYS_STUB0(x64, compat_sys_##name)
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#define __X32_COMPAT_SYS_STUBx(x, name, ...) \
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__SYS_STUBx(x64, compat_sys##name, \
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SC_X86_64_REGS_TO_ARGS(x, __VA_ARGS__))
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#define __X32_COMPAT_COND_SYSCALL(name) \
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__COND_SYSCALL(x64, compat_sys_##name)
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#else /* CONFIG_X86_X32_ABI */
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#define __X32_COMPAT_SYS_STUB0(name)
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#define __X32_COMPAT_SYS_STUBx(x, name, ...)
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#define __X32_COMPAT_COND_SYSCALL(name)
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#endif /* CONFIG_X86_X32_ABI */
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#ifdef CONFIG_COMPAT
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/*
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* Compat means IA32_EMULATION and/or X86_X32. As they use a different
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* mapping of registers to parameters, we need to generate stubs for each
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* of them.
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*/
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#define COMPAT_SYSCALL_DEFINE0(name) \
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static long \
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__do_compat_sys_##name(const struct pt_regs *__unused); \
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__IA32_COMPAT_SYS_STUB0(name) \
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__X32_COMPAT_SYS_STUB0(name) \
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static long \
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__do_compat_sys_##name(const struct pt_regs *__unused)
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#define COMPAT_SYSCALL_DEFINEx(x, name, ...) \
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static long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \
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static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\
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__IA32_COMPAT_SYS_STUBx(x, name, __VA_ARGS__) \
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__X32_COMPAT_SYS_STUBx(x, name, __VA_ARGS__) \
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static long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)) \
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{ \
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return __do_compat_sys##name(__MAP(x,__SC_DELOUSE,__VA_ARGS__));\
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} \
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static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))
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/*
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* As some compat syscalls may not be implemented, we need to expand
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* COND_SYSCALL_COMPAT in kernel/sys_ni.c to cover this case as well.
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*/
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#define COND_SYSCALL_COMPAT(name) \
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__IA32_COMPAT_COND_SYSCALL(name) \
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__X32_COMPAT_COND_SYSCALL(name)
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#endif /* CONFIG_COMPAT */
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#define __SYSCALL_DEFINEx(x, name, ...) \
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static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \
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static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));\
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__X64_SYS_STUBx(x, name, __VA_ARGS__) \
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__IA32_SYS_STUBx(x, name, __VA_ARGS__) \
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static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)) \
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{ \
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long ret = __do_sys##name(__MAP(x,__SC_CAST,__VA_ARGS__));\
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__MAP(x,__SC_TEST,__VA_ARGS__); \
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__PROTECT(x, ret,__MAP(x,__SC_ARGS,__VA_ARGS__)); \
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return ret; \
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} \
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static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))
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/*
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* As the generic SYSCALL_DEFINE0() macro does not decode any parameters for
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* obvious reasons, and passing struct pt_regs *regs to it in %rdi does not
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* hurt, we only need to re-define it here to keep the naming congruent to
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* SYSCALL_DEFINEx() -- which is essential for the COND_SYSCALL() macro
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* to work correctly.
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*/
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#define SYSCALL_DEFINE0(sname) \
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SYSCALL_METADATA(_##sname, 0); \
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static long __do_sys_##sname(const struct pt_regs *__unused); \
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__X64_SYS_STUB0(sname) \
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__IA32_SYS_STUB0(sname) \
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static long __do_sys_##sname(const struct pt_regs *__unused)
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#define COND_SYSCALL(name) \
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__X64_COND_SYSCALL(name) \
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__IA32_COND_SYSCALL(name)
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/*
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* For VSYSCALLS, we need to declare these three syscalls with the new
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* pt_regs-based calling convention for in-kernel use.
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*/
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long __x64_sys_getcpu(const struct pt_regs *regs);
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long __x64_sys_gettimeofday(const struct pt_regs *regs);
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long __x64_sys_time(const struct pt_regs *regs);
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#endif /* _ASM_X86_SYSCALL_WRAPPER_H */
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